The prelaparotomy diagnosis of extrahepatic biliary atresia.

The diagnostic accuracy of laboratory investigations in the prelaparotomy differentiation between extrahepatic biliary atresia (EHBA) and intrahepatic disease (IHD) was assessed in 86 consecutive infants presenting with conjugated hyperbilirubinaemia. Forty five infants had EHBA and 41 IHD. The mean serum bilirubin concentration, gamma-glutamyltranspeptidase (GGT) activity, and the GGT/aspartate transaminase (AST) ratio were appreciably higher in infants with EHBA than in those with IHD. In infants with IHD, however, serum bilirubin concentrations were in the EHBA range in 19 (47%), as were GGT values in 29 (71%), and GGT/AST ratios in 33 (80%). In individual patients neither increasing nor decreasing GGT values were of diagnostic importance. Failure of biliary excretion of 99Tcm-p-Butyl-ida occurred in 29 of 30 (97%) patients with EHBA but also in 22 of 23 (67%) with IHD. In all 5 patients with IHD associated with alpha 1 antitrypsin deficiency these 4 investigations gave results in the EHBA range. Liver biopsy specimen interpretation, correct in 38 of 42 infants with EHBA, gave an overall accuracy of diagnosis of 86%: the results of 3 further biopsies were equivocal. In 33 of 40 infants with IHD bile duct obstruction was excluded; the remaining 7, including 4 with alpha 1 antitrypsin deficiency, showed equivocal changes. Faecal excretion of 131I rose bengal faecal excretion was less than 10% in 36 of 37 patients with EHBA and in 9 of 26 with IHD, giving an overall accuracy of diagnosis of 84%. In patients in whom genetic disorders, such as alpha 1 antitrypsin deficiency had been excluded, interpretation of liver biopsy specimens together with 131I rose bengal faecal excretion remain the most accurate means of identifying those who need surgery for EHBA and of avoiding unnecessary laparotomy in infants with IHD.